Graphics on the ARM
Roger Amos

Graphics on the ARM

© 3QD Developments Ltd and Roger Amos


Suddenly, four years after the launch of the Acorn Archimedes in 1988, there is a new surge of interest in graphics using the Acorn 32-bit machines (which now include the A3000, A3010, A3020, A4000, A5000 and the A4 portable). This is evidenced not only in the recent introduction of a regular graphics page in the magazine BBC Acorn User, but also in a spate of graphics software and support hardware.

It is not as if the original Archimedes was unsuitable for graphics. Indeed Clares were soon on the scene with sophisticated painting, ray tracing and animation packages that made full use of the machine's 256-colour capability. With RISC OS came Draw on which many users learned the massive potential of vector and object based graphics and some found themselves baffled by its sophistication. Also with RISC OS came the sprite editor Paint, not intended as an art program but perfectly capable of being used as one, and making possible pixel based art in 16 colour and even 2 colour screen modes.

The explosion of interest coincided with the launch of RISC OS 3 in late 1991. Perhaps it was the limitations of the 256-colour palette that had held back the development of graphics on the ARM Machines. To keep the cost of the machine within the budget of the education establishments, Acorn's principal market, the video controller chip is limited to a fixed set of 256 colours or any 2, 4 or 16 from a palette of 4096 colours. For the computer artist this is either a severe restriction or a challenge, depending on viewpoint. But RISC OS 3 overcame the limitations by its support for dithering which simulates hundreds of colours in 16-colour modes and thousands in 256-colour modes.

Probably under the stimulus to improve upon Acorn's Draw, Jonathan Marten's DrawPlus was launched in 1991 followed by Vector in 1992. Both adding valuable new features and convenience to those of the original and, inspired by the drawing packages used on the PC and Macintosh machines by professional designers, Computer Concepts developed ArtWorks released in Autumn 1992.

Another stimulus has been the increasing availability of support hardware. Graphics created on Acorn machines can now be output to colour ink-jet printers capable of quality close to that produced by printing presses. Professional colour scanners with resolutions of up to 1200 clots per inch, can now he used, albeit with limitations, to convert photographs and other documents to ARM graphics. Pictures can also be imported from video sources using video digitisers, some of which cost well under £100, and if the limitations of the computer's monitor system are more than you can bear, for a few hundred pounds you can add a board to your machine which allows your monitor to display all of the 16,777,216 colours recognised by object based software.

This book provides an overview of the graphics capability of the ARM machines and tries to give a grounding in the fundamental principles underlying it. I believe that, if you understand just what the system can and cannot do, then your natural creativity will devise all sorts or fascinating new applications for it. Starting with vector graphics and moving on to pixel graphics, the book reviews some of the software available, much of it very modestly priced.

Clearly you need some artistic ability to make the most of graphics software. Perhaps artistic insight is even more valuable. This book is not a handbook of artistic techniques, but even those whose talent is modest will find that much graphics software will compensate for what is lacking, The knowledge that you can instantly undo an unfortunate operation is a source of comfort-and an encouragement to experiment with techniques previously untried.

I am indebted to the software suppliers who generously supplied products for review or who gave of their time; their constructive criticism and suggestions proved invaluable. Their names and addresses are given in Appendix 5. Nearly every company approached proved only too willing to cooperate. I am only sorry that limitations on time and energy (and on the length of this book!) made it impractical to approach every supplier. I am well aware that there is plenty more excellent graphics software available that has not been described here and so the omission of any particular package from this book must on no account be regarded as significant.

I must also set on record my thanks to the Editor of RISC User magazine, the staff of RISC Developments and to Dave and Clare Atherton of Dabs Press for their continuing support and encouragement. Special thanks are due to my nephew Simon Haslam for allowing me to pick his brains regarding the intricacies of ARM code and user access to RISC OS's internal routines, and for his patient reading of the manuscript and helpful suggestions.

Roger Amos, Rugby, November 1992

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© 3QD Developments Ltd & Roger Amos 2015